feat: add script for generating CHANGELOG.md

Author: whtsky

package.json

@@ -5,7 +5,9 @@
   "main": "index.js",
   "scripts": {
     "precommit": "lint-staged",
-    "test": "tsc && ava"
+    "test": "tsc && ava",
+    "changelog": "conventional-changelog -p angular -i CHANGELOG.md -s -r 0",
+    "version": "npm run changelog && git add CHANGELOG.md"
   },
   "author": "",
   "license": "MIT",
@@ -27,6 +29,7 @@
   },
   "devDependencies": {
     "ava": "^0.25.0",
+    "conventional-changelog-cli": "^1.3.21",
     "husky": "^0.14.3",
     "lint-staged": "^7.0.4",
     "prettier": "^1.12.0",